Roll cuboid does not work properly

Hello, I am trying to make a game, with the movement behavior, like in the game Blockorz (See gameplay video), but I can't make it roll properly. In the scripts I have used by searching this forum, I have made the cuboid to roll at the edge, but this is not working properly. I suspect its because I always use 0.5f as the half cube size, but the cuboid is a 1 width and 2 height cuboid.

Please help me, I have no clue how I can resolve this. The script I am using is this

 using UnityEngine;
 using System.Collections;
 
 public class MoveCube : MonoBehaviour {
 
     public float speed = 1.0f;
 
     private Transform pivotPoint;
     private float halfCubeSize = 1.0f;
     private bool isRotating = false;
 
     // Use this for initialization
     void Awake () {
         pivotPoint = (new GameObject("pivot")).transform;
     }
 
     // Update is called once per frame
     void Update()
     {
         if (!isRotating)
         {
             if (Input.GetKey(KeyCode.RightArrow))
             {
                 StartCoroutine(RotateCube(Vector3.right * halfCubeSize, -Vector3.forward));
             }
             else if (Input.GetKey(KeyCode.LeftArrow))
             {
                 StartCoroutine(RotateCube(-Vector3.right * halfCubeSize, Vector3.forward));
             }
             else if (Input.GetKey(KeyCode.UpArrow))
             {
                 StartCoroutine(RotateCube(Vector3.forward * halfCubeSize, Vector3.right));
             }
             else if (Input.GetKey(KeyCode.DownArrow))
             {
                 StartCoroutine(RotateCube(-Vector3.forward * halfCubeSize, -Vector3.right));
             }
         }
     }
 
     // Coroutine that rotates the cube on its bottom edges.
     IEnumerator RotateCube(Vector3 refPoint, Vector3 rotationAxis)
     {
         isRotating = true;
 
         pivotPoint.localRotation = Quaternion.identity;
         pivotPoint.position = transform.position - Vector3.up * halfCubeSize + refPoint;
 
         transform.parent = pivotPoint;
 
         float angle = 0.0f;
 
         while (angle < 90.0f)
         {
             angle += Time.deltaTime * 90.0f * speed;
             pivotPoint.rotation = Quaternion.AngleAxis(Mathf.Min(angle, 90.0f), rotationAxis);
             yield return null;
         }
 
         transform.parent = null;
         isRotating = false;
         yield return null;
     }
 }